1. Technical Field
The present invention relates in general to data communication and in particular to a method and system for wireless data communication. Still more particularly, the present invention relates to a method and system for seamless roaming between wireless data communication networks with a mobile terminal.
2. Description of the Related Art
Connectivity to wired networks continues to experience exponential growth. Likewise, recent years have seen rapid growth in the market for portable electronic devices, including portable computers and mobile telephones. It is expected in view of the growing use of portable electronic devices and the pervasive use of wired networks for entertainment, communication, and commerce that there will soon be a large demand for wireless data access to wired networks such as intranets and the Internet and World Wide Web.
Already, some standards have emerged for wireless data communication. For example, an overlay technology called CDPD (Cellular Digital Packet Data) assigns channels of an underlying radio telephony system, for example, an AMPS (Advanced Mobile Phone Service) or TDMA (Time Division Multiple Access) system, for wireless data communication. In this manner, a user of a portable electronic device (e.g., a portable computer) can establish wireless data access to the local wireless data network, which is in turn connected by a landline to the target wired network (e.g., the Internet). Another technology called GPRS (General Packet Radio Service) is integrated into the GSM (Global System for Mobile communications) protocol in order to provide wireless data access.
While the mobility of portable computer users is greatly enhanced by the availability of wireless data communication, the mobility of a portable computer is currently restricted when the user has an active session. That is, the user cannot move out of the service area of the wireless data communication network through which the user is connected to the target network without terminating the session. Thus, if the portable computer user has initiated a time consuming operation such as a download of a large file, the heretofore mobile user must remain within a confined service area if the operation is to complete successfully.
As should thus be apparent, it would be desirable to provide a method and system for data communication that permit a portable computer user to move outside the service area of a wireless data communication network through which a connection to a computer network is established without terminating an active session.